Effect of Thiourea on the Kinetics of the Hydrogen Evolution Reaction at Iron and the Transport of Hydrogen through a Steel Membrane in Solutions of C<Subscript>2</Subscript>H<Subscript>4</Subscript>(OH)<Subscript>2</Subscript>-H<Subscript>2</Subscript>O-HCl

The effect of thiourea (0.5–10 mM) on the kinetics of the hydrogen evolution reaction (HER) at iron and the hydrogen transport through a steel membrane out of ethylene glycol (containing 2 and 10 wt % H₂O) and aqueous solutions containing HCl (0.1–0.99 M) with a constant ionic strength equal to unity is studied in parallel experiments. The presence of 0.5 mM of thiourea in the solutions raises the overvoltage of hydrogen evolution, while a subsequent increase in its concentration does not effect the HER kinetics. The dependence of the flux of hydrogen diffusion through the membrane on the thiourea content passes through a maximum.     

Preparation of cyclopentadienes and diazocyclopentadienesvia cyclopentenolones and cyclopentenones

The structure and stereochemistry of the cyclopentenolones obtained by condensation of dialkyl ketones with benzil have been studied by NMR spectroscopy. These enolones were converted into cyclopentenones and cyclopentadienes. Alkyl-substituted cyclopentadienes required phenyllithium to effect their conversion by toluenesulphonyl azide into diazo-cyclopentadienes; otherwise piperidine sufficed as base catalyst.2,3,4-Triphenyldiazocyclopentadiene was simply procured by reaction of the condensation product of benzil and phenylacetone with toluenesulphonylhydrazone followed by alkali. Cyclohexyl- and methoxy-triphenylcyclopentadienes were prepared by photolytic decomposition of diazotriphenylcyclopentadiene in cyclohexane or methanol respectively.     

Magnetic behavior of copper diethyldithiocarbamate at low temperatures: A reinvestigation

The title compound, Cu(S₂CNEt₂)₂, behaves at low temperatures (1–20 K) as a normal spin-1/2 molecule, with 〈g〉 =2.06 and the Curie-Weiss θ = +0.25 K. This result contradicts an earlier investigation that led to the suggestion that the crystallographically-occurring dimers are coupled ferromagnetically.     

PVC DISULFIDE AS CATHODE MATERIALS FOR SECONDARY LITHIUM BATTERIES

PVC disulfide (2SPVC) was synthesized by solution crosslink and its molecular structure was confirmed by infrared spectrum. 2SPVC's specific area is 36.1 m2·g-1 tested by stand BET method, and granularity experiment gives out the particle size of d0.5= 11.3μm. With SEM (Scanning Electron Microscope) experiment the surface morphology and particle shape of 2SPVC were observed. Cyclic voltammetry (scan rate: 0.5 mV·s-1) shows that 2SPVC experience an obvious S-S redox reaction in charge-discharge process. When 2SPVC was used as cathode material for secondary lithium battery in a 1 mol·L-1 solution of lithium bis(trifluoromethylsulfonyl) imide (Li(CF3SO2)2N) in a 5:45:50 volume ratio mixture of o-xylene (oxy), diglyme (DG) and dimethoxymethane (DME) at 30℃, the first discharge capacity of 2SPVC is about 400.3 mAh·g-1 which is very close to its theoretical value (410.5 mAh·g-1) at a constant discharge current of 15 mA·g-1. It can retain at about 346.1 mAh·g-1 of discharge capacity after 30 charge-discharge cycles. So 2SPVC is a very promising cathode candidate for rechargeable lithium batteries.     

聚1-氨基蒽醌在二次锂电池正极材料中的应用

采用化学方法合成聚1-氨基蒽醌并用于二次锂电池正极材料,通过红外光谱、扫描电镜、粒度测试、循环伏安以及充放电测试等方法对材料的官能团结构、微观形貌、颗粒大小以及电化学性能等进行了研究与分析.实验表明,与金属锂组成二次锂电池后,聚1-氨基蒽醌达到了218.3 mAh•g－1的首次放电容量,经过25次循环后仍可保持较高的充放电效率.由于材料具有较高的能量密度且不含对环境有污染的元素S,因此是二次锂电池非常有希望的正极材料.     

Mass spectrometric diagnosis of the surface nitriding mechanism in a d.c. glow discharge

Reactive constituents have been investigated in a molecular beam generated in the cathode surface glow area and surface boundary layer. Mixtures of nitrogen and hydrogen form NH_x(x=0–4) compounds, which are of relevance in heterogeneous, plasma vs. metal nitriding reactions. Ammonia decomposition leads to NH_x(x=2–4). Strong cataphoretic enrichment of hydrogen has been observed in the cathode glow area. Heterogeneous reactions of NH_x with iron lead to the formation of iron nitrides via intermediates such as FeNH_2–3. In a pulsed d.c. glow discharge, increased sputtering and decreased hydrogen enrichment have been observed.     

Excess enthalpies of solution of some primary and secondary alcohols in sodium dodecylsulfate micellar solutions

The exces enthalpies of solution of some primary and secondary alcohols in aqueous sodium dodecylsulfate micellar solutions were measured and the results were explained by considering the distribution of alcohols between aqueous and micellar phases. The distribution constant and the enthalpy of transfer (and the standard free energy and entropy of transfer) were obtained. The thermodynamic parameters for the transfer of secondary alcohols from the aqueous to the sodium dodecylsulfate (NaDS) micellar phase differ slightly from those of the corresponding primary alcohols. For both series of alcohols the additivity rule holds for free energies of transfer whereas enthalpies and entropies display convex curves. The present data are compared to those for the transfer of the same solutes from the aqueous to the dodecyldimethylamine oxide (DDAO) and dodecyltrimethylammonium bromide (DTAB) micellar phases. The role of the hydrophilic interactions between the OH group and the micelles' head groups is formulated. The thermodynamics of the branched methyl group were determined. Furthermore, the thermodynamics of solvation of primary alcohols in water, in NaDS micelles, and in octane have been calculated using reference states based on the assumption that the empty space around alcohols in the initial and final states is the same. It is shown that the solvation of alcohols in NaDS micellar phase is enthalpy driven and that the thermodynamic properties of solvation vs. the length of the alcohol tail is the same for water and NaDS micelles whereas it is different for octane. A possible explanation for this difference is that the alkyl chain of alcohols folds in octane.     

Chemie der Pleuromutiline, 10. Mitt.: 1,2-Transposition der Carbonylfunktion im Cyclopentanonteil des tricyclischen Gerüstes

2-Hydroxy-19,20-dihydropleuromutilin (10) undergoes a stereospecific ketolisomerisation when treated with base under phase/transfer conditions (11, 12). The subsequent reductive elimination of the 3-acetoxygroup afforded mutilin with a 1,2-transposed ketofunction (13).

     

Superoxes,high temperature universal phases in (GC)2

Most of the common classes of organic compounds chromatograph normally on Superoxes. There is no tailing or adverse effect from excessively different activity different activity coefficients. Superoxes are therefore universal phases for gas chromatography. This is also expressed by a wide useful temperature range from ～50° to ～300°. High MW Superox-4 has a MAOT about 20° higher than the lower MW Superox-0.1. Several applications illustrating the versatility of Superox phases in (GC)² are presented.